This study explores the relationship between criminal activity associated with actus rea and the role of automatism, insanity, and diminished responsibility. It evaluates in what circumstances the criminal liability on the person cannot be imposed by the court. Automatism, insanity, and diminished responsibility are some examples of the barricades. The features of the automatism, insanity, and the diminished responsibility have the same features but their implementation and the range is different. The study also discusses the M’Naghten Rules (1843) and the doctrine of diminished responsibility.